Draft 2008 California 303(d)/305(b) Integrated Report

Supporting Information

Regional Board 6 - Lahontan Region

Water Body Name: West Walker River
Water Body ID: CAR6311006019980805123547
Water Body Type: River & Stream
 
DECISION ID
9914
 
Pollutant: Boron
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. Two of the annual average datapoints exceed the site-specific water quality objective. None of the samples exceeds the drinking water criterion.

Although application of Listing Policy Table 3.1 would require listing, this water body pollutant combination is not recommended for listing because the data are not temporally representative. Only one to four samples per year were collected, and the annual average objective was exceeded in two years when the "average" was based on only one or two samples. The flow data associated with the chemical samples show that boron concentrations vary significantly with flow. The few available samples do not capture the full seasonal, annual and interannual range of flows in this watershed.

Listing is also inappropriate because, except for the use of borate fire retardants to fight wildfires, boron in this watershed comes from natural geothermal sources.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy.
2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy.
3. None of 10 samples exceeded the California State Notification Level criterion. Two of 4 annual average datapoints exceeded the site-specific objective and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. However, the data on which the annual averages are based are not temporally representative.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because: (1) one of the applicable water quality standards is not being exceeded and (2) the available data are not temporally representative and are thus insufficient to assess compliance with the other standard..
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 9914
 
LOE ID: 7779
 
Pollutant: Boron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 10
Number of Exceedances: 0
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey sampled boron under the Region 6 SWAMP program between 2002 and 2005. Boron concentrations in 10 samples ranged from 12 to 134 ug/L. The criterion was not exceeded.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: The California State Notification Level criterion for boron is 1000 ug/L.
Objective/Criterion Reference: Compilation of Water Quality Goals
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Ten quarterly samples were collected between 2002 and 2005.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
LOE ID: 4924
 
Pollutant: Boron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 4
Number of Exceedances: 2
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey sampled boron under the Region 6 SWAMP program between 2002 and 2005. Boron concentrations in 10 samples ranged from 12 to 151 ug/L.
Boron concentrations varied with flow. The highest concentration, 151 ug/L was observed at an instantaneous discharge of 25 cubic feet per second (cfs) and the lowest concentration, 12 ug/L, was associated with a discharge of 1730 cfs. Annual averages (based on one to four samples per year) were 129, 104, 98, and 69 ug/L. The annual average objective was exceeded in the two years when the "average" was based on one or two samples..
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
  2000. Use Attainability Analysis for Nine "Naturally Impaired" Waters of the Lahontan Region. April 2000.
 
Water Quality Objective/Criterion: The site-specific objective for boron includes an annual average of 0.10 mg/L (= 100 ug/L) and a 90th percentile value of 0.20 mg/L (= 200 ug//L). See Lahontan Basin Plan Table 3-15.
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Ten quarterly samples were collected including one sample in 20002, two samples in 2003, four samples in 2004 and three samples in 2005. between 2002 and 2005.
Environmental Conditions: Boron in the West Walker River watershed comes almost entirely from natural sources. The most significant source of boron is probably Fales Hot Springs, although groundwater data show evidence of geothermal influence in the Antelope Valley area. The Fales Hot Springs discharge into Hot Creek, a tributary of the Little Walker River. A 1956 sample from Hot Creek had a boron concentration of 3300 ug/L. There are no point source POTW discharges in the watershed. The only known anthropogenic source of boron is the aerial application of borate fire retardants to fight wildfires.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
DECISION ID
7814
 
Pollutant: Chloride
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. None of 15 individual samples exceeded the Maximum Contaminant Level. Annual average datapoints exceeded the site-specific objective in two of four years.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy.
2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region.
3. None of 15 samples exceeded the Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. Two of four annual average datapoints exceeded the site-specific objective, but five datapoints are required for assessment using Table 3.2.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because one of the applicable water quality standards is not being exceeded and the minimum sample number requirements for assessment of compliance with the other standard are not met..
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 7814
 
LOE ID: 4925
 
Pollutant: Chloride
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 4
Number of Exceedances: 2
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey sampled chloride under the Region 6 SWAMP program between 2002 and 2005. Chloride concentrations in 12 samples ranged from 0.38 to 5.01 mg/L. The annual average objective was exceeded in two of four years.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: The site-specific objective for chloride includes an annual average of 3.0 mg/L and a 90th percentile value of 5.0 mg/L (Lahontan Basin Plan Table 3-15).
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Twelve quarterly samples were collected between 2002 and 2005. Four annual average calculations were done.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
LOE ID: 4926
 
Pollutant: Chloride
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 12
Number of Exceedances: 0
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey sampled chloride under the Region 6 SWAMP program between 2002 and 2005. Chloride concentrations in 12 samples ranged from 0.38 to 5.01 mg/L. The MCL was not exceeded.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for chloride is 250 mg/L.
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Twelve quarterly samples were collected between 2002 and 2005.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. . The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
DECISION ID
7700
 
Pollutant: Dissolved oxygen saturation
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy.
2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region.
3. None of ten samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 7700
 
LOE ID: 5729
 
Pollutant: Dissolved oxygen saturation
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Cold Freshwater Habitat
Aquatic Life Use: Fish Spawning
 
Number of Samples: 10
Number of Exceedances: 0
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey measured dissolved oxygen under the Region 6 SWAMP program. Ten samples collected between had percent saturation values 2002 and 2005 ranging from 92 to 117 percent. The objective was not violated.
Data Reference: 2007. SWAMP Data for the East Fork and West Fork Carson River Hydrologic Units.
 
Water Quality Objective/Criterion: The Lahontan Basin Plan's regionwide narrative objective for dissolved oxygen provides that percent saturation shall not be depressed more than 10 percent nor shall the minimum dissolved oxygen concentration be less than 80 percent of saturation.
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Ten samples were collected (one sample in 2002 and 9 samples at quarterly intervals between 2003 and 2005).
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
DECISION ID
7653
 
Pollutant: Fecal Coliform
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for placement on the section 303(d) list under section 3.3 of the Listing Policy. Under section 3.3 a single line of evidence is necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. One of the samples exceeds the water quality objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy.
2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and fecal coliform counts in streams of the Lahontan Region. The water quality objective calls for 5 samples collected within a 30 day period.
3. One of seven samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 7653
 
LOE ID: 5697
 
Pollutant: Fecal Coliform
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 7
Number of Exceedances: 1
 
Data and Information Type: Water column surveys (e.g. fecal coliform)
Data Used to Assess Water Quality: The U.S. Geological Survey collected quarterly samples for fecal coliform bacteria between 2003 and 2005 under the Region 6 SWAMP program. Bacteria counts in four of seven samples were estimated values. Two samples were below the detection level, and one sample was reported as greater than 240 colonies per 100 mL.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: The Lahontan Basin Plan's objective for coliform bacteria states: "Waters shall not contain concentrations of coliform organisms attributable to anthropogenic sources, including human and livestock wastes. The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml, nor shall more than 10 percent of all samples collected during any 30-day period exceed 40/100 ml. The log mean shall ideally be based on a minimum of not less than five samples collected as evenly spaced as practicable during any 30-day period. However, a log mean concentration exceeding 20/100 ml for any 30-day period shall indicate violation of this objective even if fewer than five samples were collected."
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Seven quarterly samples were collected between 2003 and 2005.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. . The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
LOE ID: 5696
 
Pollutant: Fecal Coliform
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 7
Number of Exceedances: 1
 
Data and Information Type: Water column surveys (e.g. fecal coliform)
Data Used to Assess Water Quality: The U.S. Geological Survey collected quarterly samples for fecal coliform bacteria between 2003 and 2005 under the Region 6 SWAMP program. Bacteria counts in four of seven samples were estimated values. Two samples were below the detection level, and one sample was reported as greater than 240 colonies per 100 mL.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: The Lahontan Basin Plan's objective for coliform bacteria states: "Waters shall not contain concentrations of coliform organisms attributable to anthropogenic sources, including human and livestock wastes. The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml, nor shall more than 10 percent of all samples collected during any 30-day period exceed 40/100 ml. The log mean shall ideally be based on a minimum of not less than five samples collected as evenly spaced as practicable during any 30-day period. However, a log mean concentration exceeding 20/100 ml for any 30-day period shall indicate violation of this objective even if fewer than five samples were collected."
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Seven quarterly samples were collected between 2003 and 2005.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. . The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
DECISION ID
9915
 
Pollutant: Nitrate/Nitrite (Nitrite + Nitrate as N)
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the California Maximum C.ontaminant Level (MCL).

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy.
2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region.
3. None of 12 samples exceeded the MCL and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 9915
 
LOE ID: 7777
 
Pollutant: Nitrate/Nitrite (Nitrite + Nitrate as N)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 12
Number of Exceedances: 0
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey sampled nitrite plus nitrate under the Region 6 SWAMP program between 2002 and 2005. Two of the analytical results were estimated values and one was below the detection level. Concentrations in the remaining 9 samples ranged from 0.002 to 0.149 mg/L. The MCL was not exceeded.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for nitrite plus nitrate is 10 mg/L, expressed "as nitrogen."
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Twelve quarterly samples were collected between 2002 and 2005.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
DECISION ID
7701
 
Pollutant: Oxygen, Dissolved
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceeds the water quality objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy.
2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the diel, seasonal and annual variability expected in streamflows and dissolved oxygen concentrations in streams of the Lahontan Region.
3. None of nine samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 7701
 
LOE ID: 4927
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Cold Freshwater Habitat
Aquatic Life Use: Fish Spawning
 
Number of Samples: 10
Number of Exceedances: 0
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey measured dissolved oxygen under the Region 6 SWAMP program between 2002 and 2005. Ten samples had dissolved oxygen concentrations ranging from 8.3 to 11 mg/L. The objective was not violated.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: For waters designated for the COLD and SPWN beneficial uses the 1- day minimum objective is 8 mg/L (Lahontan Basin Plan Table 3-6)
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Ten samples were collected. One sample was collected in 2002 and the remainder were collected quarterly between 2003 and 2005.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
DECISION ID
9924
 
Pollutant: Phosphorus
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status.

One line of line of evidence is available in the administrative record to assess this pollutant. Four out of four annual average datapoints exceed the site-specific water quality objective. However, listing is not recommended because the data are not temporally representative.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy.
2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the full range of seasonal and annual variabilyt expected in streamflows and constituent concentrations in streams of the Lahontan Region.
3. Four out of four annual average datapoints exceeded the site specific objective and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because, although the applicable standard is being exceeded, the data are not temporally representative.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 9924
 
LOE ID: 4929
 
Pollutant: Phosphorus
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 4
Number of Exceedances: 4
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey sampled phosphorus under the Region 6 SWAMP program between 2002 and 2005. The total phosphorus concentration in 12 samples ranged from 0.022 to 1.41 mg/L. The highest value was from an August 2004 sample and probably reflects stormwater quality from a severe thunderstorm event. The annual average objective was exceeded in 4 of 4 years.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: The site specific objective includes an annual average Total Phosphorus concentration of 0.01 mg/L and a 90th percentile value of 0.02 mg/L (Lahontan Basin Plan Table 3-15).
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: 12 samples were collected between 2002 and 2005. Four annual average calculations were done.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
DECISION ID
5587
 
Pollutant: Sedimentation/Siltation
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Delist from 303(d) list (TMDL required list)(2006)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: The West Walker River was delisted in 2006, based on State Water Board staff findings that the original listing basis was faulty due to lack of data and the fact that the original listing was in error (incorrect identification of water body). The actual issue was the failure of an irrigation diversion to Topaz Lake off the mainstem West Walker River, not the West Walker River itself. However, as a result of the 1997 flood, a significant segment of the irrigation diversion from the West Walker River to Topaz Lake (Topaz Lake diversion) was aggraded with sediment. This sediment has since been removed and the issue has been resolved.

For the 2008 Integrated Report, Lahontan Water Board staff assessed suspended sediment data collected at a station on the river. The Lahontan Basin Plan's narrative water quality objective is an antidegradation based objective that provides that there shall be no increases in suspended sediment concentrations or loads. This pollutant is being considered for placement on the section 303(d) list under section 3.10 of the Listing Policy, which deals with trends in water quality.

One line of evidence, based on quarterly sampling, is available in the administrative record to assess this pollutant. It includes 12 suspended sediment concentration values and 12 suspended sediment load values calculated from instantaneous discharge measurements.

Suspended sediment concentrations and loads are dependent on flows and can change rapidly over a short time during storm or snowmelt runoff events. Quarterly samples are insufficient to capture these short term events and therefore are insufficient to define natural background suspended sediment concentrations and loads, or to detect trends. Listing Policy Section 3.10 requires that natural background conditions be established.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy.

2. The data used do not satisfy the data quantity requirements of section 6.1.5.
Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region.
3. Sampling frequency was insufficient to establish natural background conditions and therefore does not meet the requirements of Listing Policy section 3.10.
4.. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
SWRCB Board Decision / Staff Recommendation: .
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 5587
 
LOE ID: 4931
 
Pollutant: Sediment
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 12
Number of Exceedances: 0
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey sampled the West Walker River under the Region 6 SWAMP program between 2002 and 2005. Suspended sediment concentrations in 12 samples ranged from 2 to 790 mg/L. Concurrent measurements of "instantaneous discharge" ranged from 25 to 1730 cubic feet per second. Calculated sediment loads ranged from 0.2 to 2090 tons/day. .
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: The Lahontan Basin Plan's narrative objective for suspended sediment states: "The suspended sediment load and suspended sediment discharge rate of surface waters shall not be altered in such a manner as to cause nuisance or adversely affect the water for beneficial uses."
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Twelve quarterly suspended sediment samples were collected between 2002 and 2005. Twelve load calculations were done.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, and agricultural and highway drainage. The watershed was affected by severe flooding in 1997 and wildfire in 2002. The headwaters are near the Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
LOE ID: 2859
 
Pollutant: Sedimentation/Siltation
LOE Subgroup: Testimonial Evidence
Matrix: Not Specified
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: Not Specified
Data Used to Assess Water Quality: This listing was based on best professional judgment after staff observed turbid water in an irrigation channel that diverts water from the mainstem West Walker River into Topaz Lake. No data or other information was provided. The irrigation channel was mistakenly identified as the West Walker River, resulting in its listing (in error) for sedimentation as well. The West Walker River remained on the list following the extreme flood event of 1997, due to concerns over potential impacts from flooding.

The original listing was in error (incorrect identification of water body). The actual issue was the failure of an irrigation diversion to Topaz Lake off the mainstem West Walker River, not the West Walker River itself. However, as a result of the 1997 flood, a significant segment of the irrigation diversion from the West Walker River to Topaz Lake (Topaz Lake diversion) was aggraded with sediment. The Walker River Irrigation District applied for and received permits and certifications to remove the sediment and restore the capacity of the diversion channel. The work was completed in late 2000 in accordance with the permit conditions. The sediment concerns in the Topaz Lake diversion have been resolved, and Regional Board staff is not aware of evidence to indicate current water quality standards exceedances or beneficial use impacts.
Data Reference: Placeholder reference 2006 303(d)
 
Water Quality Objective/Criterion:
Objective/Criterion Reference:
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation:
Temporal Representation:
Environmental Conditions:
QAPP Information: QA Info Missing
QAPP Information Reference(s):
 
DECISION ID
7664
 
Pollutant: Specific Conductance
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfythe data quality requirements of section 6.1.4 of the Policy.
2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region.
3. None of 12 samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 7664
 
LOE ID: 4930
 
Pollutant: Specific Conductance
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 12
Number of Exceedances: 0
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey measured specific conductance under the Region 6 SWAMP program between 2002 and 2005. Specific conductance in 12 quarterly field measurements ranged from 48 to 160 uS/cm. The MCL was not violated.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for specific conductance is 900 microsiemens per centimeter (uS/cm).
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Twelve quarterly field measurements were taken between 2002 and 2005.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
DECISION ID
7665
 
Pollutant: Sulfates
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceeds the water quality objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy.
2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region.
3. None of twelve samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 7665
 
LOE ID: 4932
 
Pollutant: Sulfates
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 12
Number of Exceedances: 0
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey sampled sulfate under the Region 6 SWAMP program between 2002 and 2005. Sulfate concentrations in 12 quarterly samples ranged from 1.7 to 10.2 mg/L. The MCL was not violated.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for sulfate is 250 mg/L.
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Twelve quarterly samples were collected between 2002 and 2005.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
DECISION ID
7699
 
Pollutant: Temperature, water
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: The Lahontan Basin Plan's narrative temperature objective is an antidegradation-based objective that requires that there be no change in temperature in waters designated for the Cold Freshwater Habitat (COLD) beneficial use. The objective does not include specific numerical limits for protection of the COLD use. Listing Policy Section 3.10 contains directions for assessment based on trends in water quality. These directions include requirements to establish specific baseline conditions and specify the influence of seasonal and interannual effects.

One line of evidence is available to support this decision. There are not enough temperature samples to establish baseline conditions (including diel, seasonal, annual and interannual variations in temperature) or to detect declining trends in the temperature regime if such trends exist.

Because temperature samples were collected only quarterly, weekly and monthly average data are not available for comparison with guidelines in the scientific literature for the temperature requirements of sensitive aquatic species such as salmonids, as directed in Listing Policy Section 6.1.5.9.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because available data are insufficient for assessment under Listing Policy Sections 3.10 and 6.1.5.9.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 7699
 
LOE ID: 4935
 
Pollutant: Temperature, water
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 12
Number of Exceedances: 0
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey measured temperature quarterly under the Region 6 SWAMP program between 2002 and 2005. Twelve water temperature measurements ranged from 1.5 to 18.5 degrees Celsius. Sampling frequency was not sufficient to determine the natural temperature range or to detect whether changes have occurred.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: The temperature objective in the Lahontan Basin Plan states: "The natural receiving water temperature of all waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such an alteration in temperature does not adversely affect the water for beneficial uses.

For waters designated WARM, water temperature shall not be altered by more than five degrees Fahrenheit ... above or below the natural temperature. For waters designated COLD, the temperature shall not be altered.

Temperature objectives for COLD interstate waters and WARM interstate waters are as specified in the 'Water Quality Control Plan for Control of Temperature in The Coastal and Interstate Waters and Enclosed Bays and Estuaries of California' including any revisions."
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Twelve quarterly temperature measurements were taken between 2002 and 2005.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, and agricultural and highway drainage. Severe streambank erosion occurred during the January 1997 flood. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
DECISION ID
7815
 
Pollutant: Total Dissolved Solids
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. None of twelve individual samples exceed the Maximum Contaminant Level. Two of four calculated annual average datapoints exceed the site-specific water quality objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy.
2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region.
3. None of twelve individual samples exceeded the Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. Two of four annual average datapoints exceeded the site-specific objective, but at least 5 datapoints are required for assessment with Table 3.2.

4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 7815
 
LOE ID: 4933
 
Pollutant: Total Dissolved Solids
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total Dissolved
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 4
Number of Exceedances: 2
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey sampled TDS under the Region 6 SWAMP program between 2002 and 2005. TDS concentrations in 12 samples analyzed as "residue" ranged from 27 to 109 mg/L. The annual average objective was violated in 2 of 4 years. An additional sample analyzed as "nonfilterable" TDS was below the detection level.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: The site-specific objective for total dissolved solids (TDS) iincludes an annual average of 60 mg/L and a 90th percentile value of 75 mg/L (Lahontan Basin Plan Table 3-15).
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Twelve quarterly samples analyzed as "residue" were collected between 2002 and 2005. Four annual average calculations were done. An additional single sample collected in May 2004 was analyzed as "nonfilterable."
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
LOE ID: 4934
 
Pollutant: Total Dissolved Solids
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total Dissolved
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 12
Number of Exceedances: 0
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey sampled TDS under the Region 6 SWAMP program between 2002 and 2005. TDS concentrations in 12 quarterly samples ranged from 27 to 109 mg/L. The MCL was not violated..
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for total dissolved solids (TDS) is 500 mg/L.
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Twelve quarterly samples were collected between 2002 and 2005.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
DECISION ID
9927
 
Pollutant: Total Kjeldahl Nitrogen (TKN)
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. No biological data are available for assessment of compliance with the water quality objective for biostimulatory substances.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy.
2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region.
3. There are no biological data available to assess whether the chemical samples exceeded the water quality objective. The data cannot be assessed using Table 3.1 of the Listing Policy.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because no biological data are available for assessment of compliance with the objective..
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 9927
 
LOE ID: 7776
 
Pollutant: Total Kjeldahl Nitrogen (TKN)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 12
Number of Exceedances: 0
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey sampled TKN under the Region 6 SWAMP program between 2002 and 2005. The TKN concentration in 12 samples ranged from 0.05 to 1.5 mg/L. The highest value was from an August 2004 sample and probably reflects stormwater quality from a severe thunderstorm event.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: There is no site-specific objective for Total Kjeldahl Nitrogen (TKN) for the West Walker River. The Lahontan Basin Plan's objective for biostimulatory substances state : "Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect the water for beneficial uses."
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Twelve quarterly samples were collected between 2002 and 2005.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
DECISION ID
9933
 
Pollutant: Total Nitrogen as N
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Two of four annual average datapoints exceed the water quality objective. However, listing is not recommended because the samples are not temporally representative and the annual averages that violate the standards include two extremely high nitrogen concentrations that probably reflect storm and spring runoff events.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy.
2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples generally do not capture the full range of variation expected in streamflow and constituent concentrations in streams of the Lahontan Region. In this case two of the samples include high flow events and skew the annual averages.

3. Two out of four annual average datapoints exceeded the site-specific water quality objective and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because although the applicable water quality standard is being exceeded, the data are not temporally representative.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 9933
 
LOE ID: 7778
 
Pollutant: Total Nitrogen as N
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 4
Number of Exceedances: 2
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey sampled the West Walker River under the Region 6 SWAMP program between 2002 and 2005. Calculated total nitrogen values included three estimated values. Concentrations in the other 9 individual samples ranged 0.06 to 1.583 mg/L. These included two very high values that probably reflected high spring runoff and a summer thunderstorm event. Two of four annual averages included estimated values. The "average" for 2002 is a single estimated value. The average for 2003, counting the below detection level value as zero and disregarding the estimated value, was 0.033 mg/L. The averages for 2004 and 2005 were 0.532 and 0.438 mg/L. Both exceeded the objective but were skewed by the high single sample values.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: The site-specific objective for total nitrogen (in Lahontan Basin Plan Table 3-15) includes an annual average of 0.20 mg/L and a 90th percentile value of 0.02 mg/L.
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Twelve quarterly samples each (1 to 4 per year) were collected for total Kjeldahl nitrogen and nitrate plus nitrite between 2002 and 2005. Concentrations of total nitrogen were calculated from these samples. Four annual averages were calculated.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
DECISION ID
9913
 
Pollutant: Turbidity
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This pollutant is being considered for placement on the section 303(d) list under sections 3.2 and 3.10 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status.

Four lines of evidence are available in the administrative record to assess this pollutant. Separate lines of evidence were prepared to assess data expressed as NTU and NTRU, since the two types of units reflect different optical properties and are not directly comparable.

Four of 8 samples expressed as NTU exceed the California Maximum Contaminant Level (MCL) applicable under the water quality objective for Chemical Constituents. The MCL is expressed as NTU, and the four samples expressed as NTRU cannot be used to determine compliance with the MCL.

The Lahontan Basin Plan's narrative objective for turbidity is antidegradation- based and allows no more than a 10 percent increase over natural turbidity levels. Listing Policy Section 3.10 provides direction for assessment of trends in water quality, including a requirement to document background conditions. Turbidity varies with streamflow and can change drastically over a single day depending on storm or snowmelt events. Continuous measurements of turbidity would be necessary to establish natural background conditions and detect trends of increased turbidity in violation of the objective. Quarterly samples are inadequate to determine complince with the narrative objective under Listing Policy Section 3.10.


Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy.
2. The dQuarterly samples do not capture the seasonal and annual variability expected in streamflows and turbidity values in streams of the Lahontan Region.ata used do not satisfy the data quantity requirements of section 6.1.5 of the Policy.
3. Four of 8 measurements expressed as NTU exceeded the MCL and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy.
4. Sampling frequency was insufficient to define background conditions or detect changes (if changes occurred). Therefore there is insufficient information to assess compliance with the narrative turbidity objective under Listing Policy Section 3.10.
5. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because one of the applicable water qualityt standards is not being exceeded and there is insufficient information to assess compliance with the other standard under Listing Policy section 3.10..
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 9913
 
LOE ID: 7751
 
Pollutant: Turbidity
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 4
Number of Exceedances: 0
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey measured turbidity quarterly under the Region 6 SWAMP program in 2004 and 2005. Turbidity values in four samples reported as NTRU included two samples below the detection level, and two samples with values of 2.6 and 54 units.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: There are no California or federal standards or criteria for turbidity expressed as NTRU. (The California Maximum Contaminant Level is 5 NTU.)
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Four quarterly turbidity measurements reported as NTRU were taken in 2004 and 2005..
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
LOE ID: 7750
 
Pollutant: Turbidity
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 4
Number of Exceedances: 0
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey measured turbidity quarterly under the Region 6 SWAMP program in 2004 and 2005. Two of four turbidity measurements reported as NTRU were below the detection level; the remaining two turbidity values were 2.6 and 54 NTRU.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: The regionwide turbidity objective in the Lahontan Basin Plan states: "Waters shall be free of changes in turbidity that cause nuisance or adversely affect the water for beneficial uses. Increases in turbidity shall not exceed natural levels by more than 10 percent."
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
  2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Four turbidity measurements reported as NTRU were taken quarterly in 2004 and 2005.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
LOE ID: 4936
 
Pollutant: Turbidity
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey measured turbidity quarterly under the Region 6 SWAMP program between 2002 and 2004. Eight laboratory turbidity samples reported as NTU ranged from 2 to 500 units. The latter value, from a sample collected August 20, 2004, was probably the result of an intense summer thunderstorm. The next highest turbidity measurement was 17 NTU.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: The regionwide turbidity objective in the Lahontan Basin Plan states: "Waters shall be free of changes in turbidity that cause nuisance or adversely affect the water for beneficial uses. Increases in turbidity shall not exceed natural levels by more than 10 percent."
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Eight quarterly turbidity measurements reported as NTU were collected between 2002 and 2004.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
LOE ID: 4937
 
Pollutant: Turbidity
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 8
Number of Exceedances: 4
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey measured turbidity quarterly under the Region 6 SWAMP program between 2002 and 2004. Eight laboratory turbidity samples reported as NTU ranged from 2 to 500 units. The latter value, from a sample collected in August 2004, was probably the result of an intense summer thunderstorm. Of the eight samples reported as NTU, four exceeded the MCL.
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for turbidity is 5 NTU.
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Eight quarterly turbidity measurements reported as NTU were taken between 2002 and 2004.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
 
DECISION ID
9934
 
Pollutant: pH
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: The Lahontan Basin Plan's narrative pH objective is an antidegradation-based objective that requires that there be no change greater than 0.5 pH units in waters designated for the Cold Freshwater Habitat (COLD) or Warm Freshwater Habitat beneficial uses. Listing Policy Section 3.10 contains directions for assessment based on trends in water quality. These directions include requirements to establish specific baseline conditions and specify the influence of seasonal and interannual effects.

One line of evidence is available to support this decision. There are not enough pH samples to establish baseline conditions (including diel, seasonal, annual and interannual variations) or to detect changes in the pH regime due to controllable factors, if such trends exist.
 
RWQCB Board Decision / Staff Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because the data are insufficient to establish baseline and trend conditions as required under section 3.10 of the Listing Policy.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 9934
 
LOE ID: 4928
 
Pollutant: pH
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 12
Number of Exceedances: 0
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: The U.S. Geological Survey measured pH quarterly under the Region 6 SWAMP program between 2002 and 2005. 12 samples had field pH values ranging from 7.4 to 8.7 units.. (The 6.5 to 8.5 unit limits do not apply to waters designated for the COLD use.)
Data Reference: 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units.
 
Water Quality Objective/Criterion: The pH objective in the North Lahontan Basin Plan states: "In fresh waters with designated beneficial uses of COLD or WARM, changes in normal ambient pH levels shall not exceed 0.5 pH units. For all other waters of the region, the pH shall not be depressed below 6.5 nor raised above 8.5 units.

The Regional Board recognizes that some waters of the Region may have natural pH levels outside of the 6.5 to 8.5 range. Compliance with the pH objective for these waters will be determined on a case-by-case basis."
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station, West Walker River near Coleville, was sampled.
Temporal Representation: Twelve quarterly pH measurements were taken between 2002 and 2005.
Environmental Conditions: The West Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage. The watershed was affected by wildfire in 2002. The headwaters near Sierra Nevada crest; Coleville is in an area transitional to Great Basin environmental conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Walker River is designated for the Spawning, Reproduction and Development use.
QAPP Information: Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):